Cable television (CATV) operators provide television service as well other services including video-on-demand, Internet connectivity and telephone service to customers via digital CATV networks. Phone companies may also provide video and data services in addition to telephone services over a digital network. Customers premise equipment (CPE) may be utilized as an interface between the customer and the digital network. Problems with services provided by the digital network often require the customer to contact the provider to attempt to troubleshoot the problem. The provider may troubleshoot the problem remotely by performing various tests on the network and the CPE. The problems may be traced to problems with the CPE, such as being installed incorrectly or being faulty. In order to fix the problems associated with the CPE a technician may be dispatched, the customer may send the CPE in for repair, or the customer may exchange the faulty CPE for new CPE
For telephone service, the CPE (Telco CPE) may provide the interface between the digital network and the analog phone service (digitize the analog phone service for transmission over the digital network, extract the analog phone service from a digital stream). A telephone may connect to the Telco CPE or the Telco CPE may utilize current phone wiring within the premise (customer phone network) to route the phone service provided by the digital network throughout the premise. The Telco CPE may connect to a phone jack in order to utilize the customer phone network. If the analog phone service (Plain Old Telephone Service (POTS)) is still active, the customer phone network may still be powered with a DC voltage. If the Telco CPE is connected to the phone jack prior to the analog phone service being deactivated, the power (DC voltage) provided to the customer phone network from the analog phone service may be provided to the Telco CPE. The power being provided to the Telco CPE may cause line faults and/or damage the Telco CPE.
FIG. 1 illustrates a high-level architecture for providing phone service over a digital network. A service provider 100 utilizes a digital network 110 to provide services to the customer. Telco CPE 120 is the interface between the digital network 110 and the customer with regard to phone service. The Telco CPE 120 may connect to the customer phone network 130 to route the telephone service to the phones 140 throughout the premise. If the customer phone network 130 is still connected to an active POTS line (has service with a POTS network), the customer phone network 130 will be powered and may damage the Telco CPE 120 when connected thereto.
Field failures of Telco CPE 120 caused by connecting the Telco CPE 120 to an active analog line is the reason for many field failures of Telco CPE 120. What is needed is a way to detect this condition and to protect the Telco CPE 120 from this condition prior to the Telco CPE 120 being damaged.